VectorReader.java

package org.regenstrief.linkage.io;

import org.regenstrief.linkage.util.*;
import org.regenstrief.linkage.*;
import java.util.*;

/**
 * This DataSourceReader holds one Record that is explicitly given
 * in the LinkDataSource object.  There are multiple constructors:
 * 
 * (LinkDataSource, MatchingConfig) - this constructor does not use the MatchingCofnig
 * object in any way, but mirrors how an ordered reader would be instantiated.  Since there is
 * just one Record, there is no other orders in which to return it.  The LinkDataSource is parsed in 
 * the same way as in the constructor without the MatchingConfig object.
 * 
 * (LinkDataSource) - this constructor parses the information to get the field values for
 * the one Record described.
 * 
 * (Record) - this constructor just stores this given Record to be read later.
 *
 */

public class VectorReader implements DataSourceReader, OrderedDataSourceReader{
	private LinkDataSource data_source;
	
	private boolean accessed;
	private Record data;
	
	/**
	 * This constructor uses the same format as the DataSourceReader
	 * superclass and uses the information held within the LinkDataSource
	 * object to get field values directly.
	 * 
	 * @param lds	the LinkDataSource object with field values
	 * @param mc	the MatchingConfigObject to determine sort order
	 */
	public VectorReader(LinkDataSource lds, MatchingConfig mc){
		data_source = lds;
		accessed = false;
		data = buildRecord(lds);
	}
	
	public VectorReader(LinkDataSource lds){
		data_source = lds;
		accessed = false;
		data = buildRecord(lds);
	}
	
	/**
	 * An alternate method of creating the VectorReader object that will return
	 * the given Record instead of constructing it from a LinkDataSource object.
	 * 
	 * @param r	the Record to be returned when nextRecord() is called
	 */
	public VectorReader(Record r){
		data_source = null;
		accessed = false;
		data = r;
	}
	
	/**
	 * Returns the number of fields within the Record object.
	 */
	public int getRecordSize(){
		return data.getDemographics().size();
	}
	
	/*
	 * Gets the values from the LinkDataSource object and makes a Record object
	 * from it. 
	 * 
	 * @param lds	LinkDataSource with the field names and values
	 * @return	the Record holding the LinkDataSource information
	 */
	private Record buildRecord(LinkDataSource lds){
		Record data = new Record(0, lds.getName());
		Iterator<DataColumn> it = lds.getDataColumns().iterator();
		while(it.hasNext()){
			DataColumn dc = it.next();
			if(dc.getIncludePosition() != DataColumn.INCLUDE_NA){
				data.addDemographic(dc.getName(), dc.getColumnID());
			}
		}
		
		return data;
	}
	
	/*
	 * can just use a flag to see if the one Record has been returned yet
	 */
	public boolean hasNextRecord() {
		return !accessed;
	}
	
	public Record nextRecord() {
		if(!accessed){
			accessed = true;
			return data;
		}
		return null;
	}
	
	public boolean reset() {
		accessed = false;
		return true;
	}
	
	public boolean close(){
		data = null;
		return true;
	}

}